You need to decide what you want from the hotel. My instinct as somone who lives in London is this:

"London has no true luxury hotels. You should therefore choose a five star that suits your location or has been recently refurbished or has a good special offer."

Slightly sad but true and, given what you said about service not being a major issue, realistic for you. I would therefore put The Mayfair back on the list, because they spent a fortune on it and it looks very good. You could put the InterCon on there for the same reason, as well as the Lowndes. The Savoy is likely to be a good bet since it will have good opening deals and will look lovely. I understand the rooms at the Langham have not been done, only the suites, so scrub that. Connaught has been fully redone and should be a decent bet.

Location is a red herring. Get a map out, there is a huge distance between the Tower of London and the South Kensington museums, which are the left and right hand edges of most tourist maps. Anything on here will be fine. The Soho Hotel is tucked inbetween the bars and brothels of Soho which may or may not be an issue for you, but modern and the funkiest on the list.